I'm going to try a recommended solution involving disabling Safe Sleep mode which a number of folks have pointed to as a possible culprit. There is an application that will do the job or you can disable in terminal mode. http://www.jinx.de/SmartSleep.html
To disable safe sleep, run the two following commands in Terminal:
$ sudo pmset -a hibernatemode 0
$ sudo nvram "use-nvramrc?"=false
When done, restart your computer. Now go delete the file /private var vm sleepimage" to free up some hard drive space. When you put your computer to sleep it, should happen in under five seconds; my MacBook now goes to sleep in two seconds.